Whats wrong with my lower eye lid?

normally i wear contacts i have been wearing them for over 6 months and i have never had a problem until now. yesterday at night my when i rubbed my eye lids on the left side it dint hurt but i had some discomfort so i took off my contacts and when i woke up today my lower eye lid was swollen. i can see perfectly, its not painfull, its just my lower eye lid..whats wrong??tanks...should i go to the doctor or i can fix it going to walgreens???