Formula Advice

I’m a first time mom and have a 4 week old. I had some problems breastfeeding, so I had to turn to formula so my baby won’t starve. I had given up BF and just continued giving him formula. We give him Enfamil Infant. Now he’s really fussy, looks bloated all the time, and looks like he has trouble pooping. When he’s pooping, he does this little noise and what sounds like he forces his poop out.

Now I’m not sure what to do... If it’s the formula we are giving him that’s making him that way or if it’s normal.

Should I switch his formula? If so, do I have to go to his pediatrician first before so?

please help.