Trouble with Lentils and some Dairy

Hello friends!

I'm 2.5 months  VGSleeve post-op and I can't have Milk, yogurt or Ice Cream. other dairy is fine like cheese and sour cream. But for some reason milk and ice cream (my fav) gives me extreme stomach pain (no diarrhea). The pain can be so bad that I'll have to lay down for 15-20 minutes before it goes away. It doesnt feel like gas either, it's more of a cramping pain. 

Last night I made yellow lentils with spinach (an Indian dish) and the same stomach pain came. After laying down for 20 minutes I was fine. 

To rule out other thoughts:

Peanuts are fine

beans are fine (black and red)

Indian food is fine (my husband is from India and I cook A LOT of indian food)

Cheese is fine

Sour Cream is fine

I had a lap-band surgery in 2013 and I experienced some lactose sensitivity (including diarrhea) . That went away after a month or so. 

I can deal with the diary (byebye ice cream)

But lentils.... AHH I dont know if I can deal with this. 

has anyone else experienced this? Is there a similar protein in milk and lentils? 

Thanks for your input.

I developed food allergies.. if i eat some foods that I am allergic to - I get cramps and pain... 

it may be lactose still (is in milk and ice cream but not in cheese). as fo lentils - yu may be allergic to them,..

BTW: I am allergic to vanilla, bananas, pineapple, soy, dairy (all of it- even cheese) etc etc.. 

so I need to be careful.