you could have bed bugs in your mattress only while other familymembers are spared - that's one possibility. You could also have a fungal infection, a sensitivity to something new in your environment (skin contact dermatitis) so I'd hasten to a dermatologist and get an official medical examination.
You can try a colloidal oatmeal bath and Aveeno anti-itch cream to soothe it and try Benadryl as well, but you do need to get a medical opinion.