Birth Control & period (TMI)

I have been off and on birth control (pill) for about 12 years. Recently I stopped taking birth control in January 2016 and just went back on a month ago. (just finished 1st week of 2nd pack) What I usually do is skip the iron pills and go right to birth control, therefore skipping my period. However, this time I got my period anyway. Which is fine ... & annoying... Except the lining that I am losing is thicker and the period is lasting longer than usual. My cycle is usually 4 days (avg) and very light by now. I am in day 5 and its appears to be heavy. What is worrisome to me is how thick the clots/lining is and how long I am still bleeding. On the 3rd day there was a very thick and long piece of lining on the pad which worry me. Now I am starting to cramp (which I usually starts in the beginning of period - not 5 days in) among other period symptoms that are usually gone by now.

Guess I am writing this to see if anyone else experience anything like I have been.