Agree with above poster and would like to add one thing: some animals will develop obsessive behaviors as a way to deal with stress - one of these being compulsive licking. I think it is more common in dogs but you might want to see if anything has changed in her environment/routine that would trigger any stress or anxiety.
Here is a good article about compulsive behavior in cats from the ASPCA:
http://www.aspcabehavior.org/articles/97/Compulsive-Behavior-in-Cats.aspx
hi and welcome,
when the irritation is on the paw than its likely more to do with a sensitivity to something the paw is coming in contact with ie: LITTER..if its a scented type change to non-scented, change the brand in any case. also could try a natural rather than a clay...such a paper or crystal litter avail at pet stores.
also carpets....could be an allergy to the carpet..do you have wool?
floorings what do you use for a cleaner? something harsh like bleach or any chemical? stop and use vinegar only.
if kitty goes outdoors...is there something out there she is walking on? such as grass fertilizer or other chemicals?
try to think of anything that her paw may come in contact with...this is very likely a CONTACT allergy.
if we can help more please post again, but start with that...good luck.