Help with my 2.5 year old

So I wasn't sure where to post this but figured any advice would be great. We (my son and I) have been staying with my parents since the beginning of August. Some weekends we go home when Daddy is off of work other times we stay and hubby comes out to visit when he can. Everything was going well until about three weeks ago - my son started having these crying fits and hitting or pushing down his younger cousin or pulling the older ones hair (he stays with my sister for part of the week so I can relax and sleep in). Lately he has been waking 2-3 times a night. He has no fever but he has been teething and the molars have finally come through. I have tried every form of discipline with him and it seems for the most part 10 seconds after he gets out of time out he is doing it again. I though maybe he is just overwhelmed with the kids at my sisters because essentially here and at home he is an only child (my step son is there only every other weekend). Then I thought it was all the house switching back and forth but then I figured we would of had trouble from the very beginning. I have also tried putting him to nap and bed earlier as maybe he is overtired. This week my mom and I are trying a gluten free diet to see if maybe he has a mild food allergy and for the first two days I thought we were on to something, then my sister came over last night with her girls to pick him up and it wasn't 45sec they were in the house he knocked the littlest one down for nothing. Anyone have any ideas????
And on another note, we have been attempting potty training on and off when he is interested but I've noticed his BM's are not really formed so to speak and shouldn't they be by this age??? I have thought about taking him in to see his pediatrician for a overall check up in case maybe I am missing an ear infection or something (my mom says my brother never cried or pulled at his ears but his behavior would go downhill) but I am afriad I will get laughed out of there as he has no fever and otherwise is eating, playing and sleeping (other than the behavior acting normal).

[angelbabies]

sounds like normal 2 year old, he might be stressed or upset mayb with change, you being pregnant?

mayb try talking to him or playing a game where you can talk to him about his feelings?
try to avoid fizzy drinks or sweets that could make things worce!
it might just be a cry ofr attenshon mayb just allocate the same hour every day to him so he knows this is your time with him to play or dont what he would like and have lots of cuddles, might just help dose he know your pregnant? b/c he might no compleatly undersand that or feel left out?

i realy dont no though i dont no though without knowing your child its hard to advise you
good luck xx

[Atlantisea]

Maybe he is missing you and just after some extra attention?
He might think that if he is naughty he will be sent home or not have to leave with your sister..
Definitely see a doctor and rule out medical causes just in case.

[sadiesmommy]

Thanks ladies so much. I am sure he is probably stressed about the whole situation (who wouldn't be) and so I have tried to make the changes as routine as possible but its tough to see your child is the little bully - makes me want to cry when I think that its the only way he thinks he can get my attention. Against my husbands wishes I did keep him here with me all week last week just to see if that would make a difference every once in awhile for him to know that he is not leaving his momma no matter how he behaves and I talked to my sister this morning and she said that he has been fine and even slept through the night last night so that was a huge relief. I was utterly exhausted at the end of last week but knowing that my child isn't being a terror to my nieces is worth it - plus last night I slept the best I had in probably the last month being pregnant (LOL). I know it probably isn't the greatest thing for me to do but maybe if I am up to it every couple of weeks and give the kids time away from one another and my sister some time off and Aiden some time alone with me it will all work out. For his sake I cannot wait until its all over and we are back home again!!! Thanks for the advice and for listening (as always).