I don't know what to do..

He just turned 2 months old. 

At first we thought maybe he was constipated but he pooped today in the early AM. 

He's been on enfamil gentle ease but I just switched him to gerber soothe last night.

Now today he's still fussy, screaming and crying. He went to sleep and woke up after 30 min - 1 hour screaming and crying. It looked like he was pushing so I thought he was pooping but he had nothing in his diaper. He started farting and would scream/cry when he would fart. I tried doing bicycle legs and massaging his tummy but still no poop. He wouldn't stop crying screaming even though we kept bouncing him and rocking him and he didn't want his pacifier and wasn't hungry. After crying for so long he finally fell asleep.

Could it be the gerber soothe formula?

I just started giving it to him last night though could it be affecting him already? Should I switch back to enfamil? Or should I just wait it out? I heard good things about the gerber formula but so far I don't see any results..

Could it be gas? Or is he constipated? 

Maybe sleepy? Is this normal?

I don't know what to do or what else to try..

I'm a FTM and feeling like I'm not doing a good job..any help/suggestions are greatly appreciated.

Thanks ladies.