Child oral thrush hysterically crying! Help!!

My little boy (almost 2) has oral thrush, he's gad it once before but not like this. He hasnt been himself for a while now, I know it can be very uncomfortable for them but he's been having times where he is screaming for ages! He wants to be held and won't let me sit down, this is very unusual for him. Tonught he has woken in the night screamming and I can't stop him, I don't know what to do! Iv given him calpol and he has a gel for his mouth, could something else be going on??