Would suggest that you are on the right track when considering insect cause. Investigation of mites, domestic animal type might be helpful. Look into Vet websites and some derm specific sites also.
With luck you've lost the critters by now.
Ta
Dr., I have the same exact problem as the man above, and went to my doctor about it... he also said it was striae, but i had not gained any weight recently and i also have not started excersizing. I saw on TV a report about this condition, relating to a tick-spread bacterium. Do you know anything about this? thanks.
These sound like striae, colloqially referred to as "stretch marks." These occur in the following contexts: pergnancy, obesity, using strong cortisone creams, exercising such as weight lifting. Not much can be done for them, but Retin-A cream can help make them fade from red to off-white faster than they would otherwise. I suggest you show a doctor for definitive diagnosis.
Best.
Dr. Rockoff