sleep regression at 3 months

Hi all. My LO is 3 months (15 weeks to be exact) and for a couple of weeks now, she's been very fussy and would just sleep for 30-40 naps. The night time sleeping is great but her nap times are awful. She would always cry and always wants to be held. I was thinking that maybe it's a growth spurt because last week all she wanted to do was to nurse. But with the crazy nap schedule she's giving us makes me want to think she's in a sleep regression - or maybe both growth spurt and sleep regression! Can this happen or can sleep regression happen at 15 weeks (please take note this started happening a week before as well)? I keep reading that it happens at 4 months. Thanks!