My 2 year old son has some really swollen itchy bug bites what can i give him? can i give him a low dose of benadryl because i've already tried creams

Yes you can: but only 2.5 ml, every 4-6 hours, as needed and don't exceed 30 mg in 24 hours from all sources. You can can also use OTC hydrocortisone cream 1% ,, if you haven't used that already, you can apply it on affected areas twice a day till symptoms improve. If no improvement in a day or two, or symptoms develop, see his pediatrician or dermatologist, wish you both wellness