20m 6’2 155lbs and am struggling bad with my weight

As the title says I’m a 20m and I come from a family of high metabolism and skinny people.

Growing up I wrestled which meant constant fasting and weight cutting. Plus I’m extremely adhd so I was always on meds that would make me not eat.

Well recently I went to the dr and they are sending me to a GI specialist. They said I was pretty underweight, and have possible chronic nausea which I don’t even know what that means.

I’ve been struggling with this all my life and any insight would help.

Symptoms:

Extreme loss of appetite on sight or smell of food.

Can’t stomach dry or fat heavy foods.

Body reaction and gagging to swallowing food even though I haven’t eaten and am hungry.

That being said I work in construction and am in the gym 3-5 times a day I have no energy at all ever I feel like a walking corpse.