My 22lb 15 month old son has hand foot and mouth disease can I give him Benadryl (diphenhydramine) or can I rub a itch cream on it???

No itch cream. typically, hand, foot mouth disease is most worrisome because the oral lesions, and possible associated fever will cause a loss of appetite, and an increased risk of dehydration. the lesions are not usually itchy, and benadryl might not help at all. i would definitely avoid any topical creams, as they could be accidentally ingested. I would recommend tylenol (acetaminophen) at usual doses.
Yes you can. If he has a rash on his hands and feet and it is itchy, you can give oral Benadryl (diphenhydramine). That will probably help more than a cream, but a 1% hydrocortisone cream can also be used, but not on him hands. If the rash is not itchy, there is no need to give either. Are you giving him a pain medication for the sores in the throat and mouth (the most common symptom of this disease)?
Yes. You can give him 5 mg( don't know in teaspoons because it depends on the concentration you buy so read the label closely) every 6 hours. Do not put cremes in open sores or fresh skin.