increase appetite and weight gain

Thank you for the quick reply. Developmently, he is behind in both speech and physical movement and sees a specialist for both - but has been evaluated and has no mental disabilities. Core muscle strength is lower than average - which is why his speech therapist thinks he has aversions to difficult to eat food. Likes to eat sweet, smooth things like yogurt, milk (we use almond milk) - also likes mac and cheese and snack food like goldfish. Does not like multi - textured food - like meat and cheese sandwich. Behaviourly, plays well with other kids, loves balls and trains. Not sure about the dreams or temp. preference - but sleeps about 12 hrs at night with 2-3 hr nap. I used to feed him dinner - but recently he refuses to eat the food I put in his mouth - will hold the same bite of food for up to 20 min without chewing or swallowing. Has been waking up the last few nights around 1 or 2 am wanting milk - probably due to eating no dinner. Sucks his thumb - not sure if that is relevant. Has slight dairy allergy - which is why we use almond milk. Thanks