It is not mandatory, nor necessary to use antibiotics during a medical abortion. Some people recommend to use antibiotics to prevent infections after using abortion pills, however this is not necessary in most cases. Remember the risk of getting an infection is very low (less than 1%), and most women do not have an infection after the procedure.
If you suspect you have an infection, you need to get medical care so they can diagnose you correctly. If they confirm you have an infection, they will prescribe you with an adequate treatment for your case.