Hives from cephalexin?

I started taking it Thursday night due to a belly piercing infection and ever since then my legs have been itching a lot and I’m pretty sure it’s due to the antibiotics. I have taken this medication before and I have had a little itching but not as much as this. I have to go back to the doctor for a follow up in a few days should I let him know about the itching? I have a penicillin allergy so idk if it’s related to that medicine.