It is gas.
My daughter had a bad time with gas... she RARELY farted or burped as a baby. Though I tried.
Remember, their internal organs are not fully developed yet.
Either.
Thus, they get gas.
Use Mylicon Infant Gas Drops.
It helped my daughter a ton.
Also, don't eat things that cause gas. It will get in the breastmilk.
And, make sure he is latching on properly.
If not, he will not be getting proper intake.
The ENTIRE areola, should be in his mouth. The baby should not just be on the tip of the nipple.
CONTINUE nursing him.
Use Mylicon Infant Gas Drops.
My daughter was like that... and I nursed her until she self-weaned at about 2.5 years old and she grew like a weed.
This is not colic.
Because, it is only happening when he is at breast.
Also, it could be that he is not latching on properly or he does not know how to suck to get the let-down going. Or if you have a slow or too-fast, let down. A baby will fuss due to those reasons too.
See a Lactation Consultant.
This should be your 1st, person to check with.
As you said, after he farts... he feels better.
He has Gas.
My daughter was JUST like that.
I still nursed.
We gave her the infant gas drops.
My daughter, had a hard time passing gas as an infant.
This lasted for about her 1st 3-4 months.
Until her organs, matured.
And you said, the reflux meds did NOT help.
Don't give him stuff... all kinds of stuff. He is only 7 weeks.
Try the infant gas drops, first and/or see a Lactation Consultant... to make sure it is not ALSO...gas AND a poor latch, too. Or a poor let-down or too fast, let-down of milk.
And, are you producing enough milk?
If not, infants get fussy for that reason too.
The arched back and clenched fists and straight legs...are ALL classic symptoms, of Gas. Pain.
My daughter did that as a baby.
She had BAD gas.
NOT reflux.
Gently massage his tummy in circular motions as well and bicycle his legs and burp him often.