Daytime sleeping

HI, my daughter is 12 weeks old and up until 2 weeks ago she wouldn't sleed in the day either i tried everything also, and she would only go to sleep while i was cuddling her then she wouldn't even do that after a while. The trouble was that she was so tired i knew she needed to sleep, i wouldn't have minded her not sleeping if i knew that she wasn't tired but she was so misarable all the time she would just cry all day even when i tried to entertain her, then one day i was a complete mess, she was crying so much because she was tired it made me cry and i had to leave to cry in her bed for ages, i gave her her dummy and put her musical toy on which lights up and plays peaceful music and after about 3 hrs she fell asleep. Since then it has been a lot better she has about 2-3hrs sleep in te afternoon which is brilliant and she is so much happier. i Know leaving her to cry for so long wasn't nice but i did keep checking she was ok and it was for her own good. All of you who have this problem i'm sure it will sort itself out, i don't think ther is a right or wrong way of doing things you just have to do what you think is best. x