We have quite a few food intolerances in the family, and I am ‘developing’ most of them as time passes. Am now in my 50s and my body copes far less well with these things nowadays.
This is how it seems to work - based on personal experience, and seeing other people go through the same thing:
You are young, fit, active, with a bouncingly healthy immune system.
Yeah, your family are all old crocks with all the weird sickly food intolerances that make them such tiresomely fussy eaters, but hey, that doesn’t apply to YOU! You are invincible. And very young.
As time passes, maybe you start to get a few very minor signs, of intolerance (maybe a bit of brain fog after a 4 cheese pizza with icecream to follow) but that is OK, you can still eat the stuff. No worries.
More time passes and maybe the pizza gives you indigestion now. And maybe that affects your sleep. So you cut back. A bit. Still no worries. I mean, everyone gets indigestion occasionally, don’t they? And there are antacids. No big deal. You are NOT going to turn into your mother. That is unacceptable.
Then it gets to the stage where you kind of can’t ignore it anymore. Antacids are pretty vile. The gas is embarrassing. You say goodbye to 4 cheese pizza, but still have a meat feast occasionally. But eventually think ‘It just isn’t worth it’ and switch to another Takeaway choice (with less dairy), to the disgust of your indestructable husband.
Then, eventually, you have to admit there is a problem, and you do a bit of reading, and you discover that Exclusion Diets can help you identify the problem.
So you cut out dairy completely. For weeks. And feel great. But it is a gradual improvement and v hard to assess. So you give dairy a controlled trial (cos you miss it soooooo much!), and OMG! the symptoms are back 10x as bad and this is ABSURD!!!
(I think this is where you are at, @Karlos , yes?)
But you can’t quite believe it, so you push the boundaries and do a bit more testing, and the symptoms ease up. Almost as if your body had lost the capacity to cope with Dairy while on the exclusion diet, but now it is learning all over again… and your tolerance is building up again.
So now you have to decide what to do:
Option 1
Cut all dairy for ever and feel great for ever, unless you accidentally ingest some sneaky hidden dairy, and it wipes you out for a day or more. In many ways, the less you eat of an intolerance food, the more sensitive to it you get. Which sucks. A lot.
Option 2
Decide that these intolerances are nonsense and I WILL NOT BE BEATEN BY A GLUG OF CREAM. In which case you will go back to eating it regularly and never feeling great, but also not feeling awful, and the symptoms will slowly escalate, while your immune system strugges to cope, and in a few years you will find you have to reassess. Or you will become really ill and your immune system will break down in another, equally irritating way. A rash. Psoriasis. Inflamed joints. Whatever. It won’t be fun. I know.
Option 3
Explore to find out exactly what is going on, and then tailor your diet to suit your body. In my case the problem is whey, not lactose. It isn’t always lactose, though that is the assumption everyone seems to make. So I get to eat hard cheese, thick cream and butter, but milk, yoghurt and most soft cheeses have too much whey and make me feel like I have been run over by an angry bus.
I can eat goats milk fine.
Option 4
Give up on dairy. (and then discover that soy is worse than dairy - yup, voice of experience)
As you can see, I have been down this route. With dairy, soy, wheat, then gluten and grains. Each time, the same thing has happened. Textbook little path from denial, through anger, grief, depression and eventually resentful acceptance 
I am only in my 50s. So I know there is more to come - from watching the relatives on one side of my family go through this. I had an aunt with the most terrible indigestion. She was a martyr to it. For decades. But she never admitted or believed that what she was eating could reduce her suffering. So she just carried on eating as normal. Popping the antacids. And guess what, her guts gave out completely, in her 80s. She died of bowel cancer. I have no proof that her cancer, her antacids and her lifelong stomach issues were connected. But it makes me wonder.
Sorry for the long post. But I wanted to show that you aren’t alone in any of it, and that the stages are pretty predictable. Hopefully you can fast track a couple of stages (or shortcut around them) to find a workable long term solution to incorporate foods you love.
