Do I have breakthrough bleeding?

so i have taken birth control for about 5 years i am 21 years old but i am about 2 weeks into my pills and i started spotting. the spotting turning into like my full blown period only fairly heavy sometimes there are like "clots" that come out ... should i be worried? also i heard it could be because my body is too used to my pills and i should get a stronger perscription? and also any idea how long i can expect this bleeding to last? :( all help is very needed! thanks!!