My infant son has strange skin markings on his leg?

Last night my 14 month old son woke, whilst changing his nappy I noticed strange skin markings on the inside of his thigh. They appeared to be roman numerals, where quite outstanding , raised, red marks. He didn't have them before bed and we checked his pants he'd been wearing and his bed clothes but can;t work it out. I ended up taking photos of the marks this morning after he woke because they were still there however quite a bit fainter. They look like V V backwards Z I Y 11 upsidedown 7. I wish I had of taken photos last night when they were more pronounced. Any ideas? my husband didn't know what they could be but he's also not that worried about them. If anyone could help I'll send photos to you. Thanks packa76