Bugs love me so I have plenty of experience with being bitten. ;ol
Fleas get into clothing and like to bite in tight places, along an elastic waistband for example. They also bite several times and you might see a trail of bites in a row. If they are living in the carpet, you might get a bite or two on the lower leg as they jump up for a taste and then back off to wait for the next warm body to come by.
Bites on areas exposed at night might be from a lone mosquito. Especially if there are just one or two bites each night, there may be a mosquito hanging out in the bedroom, getting it's daily meal while you sleep and then hiding til the next night.
Spider bites often look like 2 red dots from their 2 fangs. yuck.
Best product I've found to relieve the itching and swelling of bug bites is Benadryl gel. I really slather the stuff on and the bites seem to dry up and go away faster.