HELP! crying baby!

My baby is 6 weeks old and has been crying uncontrollably for 2hrs straight. My husband and I have tried everything to figure out what's wrong. Did the windi to relieve gas, took his temperature, rocked him, tried singing to him. Cleaned his diaper and fed him. He felt super hot so I checked his temp 3x and it was around 99.6. We fianally took his short sleeve light onesie off and he has managed to stay a little less fussy but only when held. The back of his head and back were sweaty even though it's not hot and he doesn't have a fever. Has this happened to anyone? Why is our baby so hot? I'm not even sure if that's the problem but it's the first time it's happened...