M.P.
I just want to tell you - I feel your pain!! My husband and I took our then 10 month old son on a LONG trip to Colorado and after two days of traveling my son started screaming during the night, getting sores on the ends of his fingers and on the inside of his mouth, and throwing up all food (probably because the sores ran down the inside of his throat). We were staying at 8500 feet in the wilderness with not one doctor around and when I called mine back in Roseville they suggested we bring him in (yea, right!) because they have to diagnose him. So I called an old friend in the nearest town and called her doc and he said they couldn't see him because he wasn't a patient of theirs. I did have internet access however and just started researching. I figured it had to be hand, foot and mouth disease and it's a virus - sometimes passed along via feces (yuck!), which would also explain how we picked it up traveling or on a diaper changing table (our car was too full to change in) and has to run it's course, unfortunately. I was told it would take over 3 weeks to be rid of it and nothing really helps. Then to top things off, my husband got it! They say adults don't tend to get it, but he did.... and once an adult can explain how uncomfortable it is, poor things.... anyway, my husband ended up taking a week off from work once we got back from driving another 2 days (and that's 12 hours each day) back to Cali. Oh, the joys of motherhood....
My husband would tell me when he took a shower it would hurt more, because the water hitting the sores would be painful. It felt to him as if he'd been "working in a field all day". But the good news is it will run it's course. I would say if the sores have lasted longer than 2 weeks definately go and see a doc, at least they can put your fears to rest, and with a weak immune system that may be what you need to do.
I don't know what help this is, if any, probably none! But good luck, always remember... "and this too shall pass"
God Bless