Bruised knees from crawling

Morning ladies,

Was just wondering if anyone's elses LO's ended up with bruised knees when they started crawling?

Isla has been crawling for about 3 or 4 months but over the last few weeks I've noticed little bruises appearing on her knees but now they look truly awful as theres loads! They don't seem to bother her and she's still crawling on them enthusiastically, but I'm even a bit nervy to take her to the HV to get weighed incase they think it's something sinister!!!

Did anyone have these appear?

Thanks
Love N & Isla (10 months) xxx