Bites on ankles a couple on feet while sleeping?

a couple days ago i began to notice bites on my ankles they r like 3 in a row and a couple on my feet i checked the bed and matress topper to see if there was any bugs or spiders i can see none.. we bought a stray dog in here about a month ago kept him for a week and gave him to someone 3 weeks ago so i dont know if its fleas or not as its been 3 weeks since the dog has been gone anyone have any idea what they could be they r only on my feet and ankles