Period

i have an irregular cycle. sometimes i didnt even get a cycle until my doctor put me on birthcontrol pills. and my period came normally, on time, and went off on time every month. the pills were giving me leg pains, so i stopped taking them. now that im not on the pills, every month around the time when im supposed to get my period i just get brown discharge. and its scaring me! is it anything to be worried about?