Unexpected Hormonal problems with Birth control pills. Help please.?

For two years straight, i used Mercilon but then i decided to stop for awhile at the end of last year, no particular reason, my lover and i decided to just use condoms for awhile. I have always trusted Mercilon and it has never given me any problems, not at all. So 3 months ago i started on Mercilon again and for the past 3 months of using it, ive been too sensitive and would get annoyed or angry at the tiniest things. Also, crying was always an easy task. Why is it giving me problems now? My hormones are going nuts! So im thinking about switching pills, i would like some tips on how and which brand? Thank you so much <3