I was a lacto ovo vegetarian for over a decade. It's so much better than vegan. Vegans can't get taurine from food except by eating a tonne of seaweed. Vegan iron isn't well absorbed like heme iron is. Plant based calcium too - veganism is linked to osteoporosis and anemia. I hope your microbiome will heal in time. Try fresh cheeses like havarti, mozzarella, and mild cheddar. Aged cheese has a lot of histamine and milk is so fresh that is can be upsetting. Mild cheeses, ypgoirt and spur cream are already partially digested by bacteria so less stress on the stomach. I drink lactose free milk like Dairy land Fair Life. It has more protein and less sugar than regular milk and doesn't bug my stomach. I also use organic cream a lot. The higher fat content helps somehow. As for eggs, nothing wrong with free range eggs. The chickens run around outside and in a coop (free range, not free run). You're not eating a baby chick, after all. An egg is a haploid gamete cell. Yes, there's the baby rooster issue and it's morbid, but eating an egg isn't the worst thing ever. I'd rather eat a free range egg from a cardboard carton than buy overprocessed fake meat that's quadruple the price and sealed in plastic that never breaks down. I also eat free range organic grass fed beef too, in moderation as well as organic free range chicken and line caught wild fish from local fisherpeople. It's called ethical omnivorism. Vegans hate that term but I don't care. I'm allergic to nuts and see way too many malnourished vegans.

I am old and I tried to be a vegetarian in the 1970s and last 6 months before getting tired of:

1 - starving and
2 - looking down at meat eaters.

There's such a range of lactose-free and low-lactose dairy available!