Hey there.
I’m 23 and I’ve had the same exact problem ever since I was 11-12 I think, except, I have more sweat on my palms than my feet, but definitely heavy sweat underarms and some on my feet too. My palms are so sweaty exam papers usually curl up under my palm.
The sweat under my arms usually stinks too, so I use something that has literally changed my life, and that is Rubbing Alcohol (i.e. 70% Isopropyl Alcohol) on it before wearing my shirt every day. I’ll usually have to wash and re-apply it every time I change though.
As for the wetness and the sweat itself though, I go through the exact same thing. When happy, excited, or even when I’m internally or unconsciously anxious/happy/nervous I sweat excessively. It is really a big social problem, because I always have to think about what to wear so that the stain is not visible. I do try to mentally cool down whenever that happens, but that’s not always possible, because it’s a bit difficult to un-happy yourself!
It’s funny though because when everyone else is sweating (say at a club or when dancing), I don’t really sweat! I’ve read about botox injections, but I wouldn’t wanna do that because I have recently been diagnosed with MS and I’ll do anything to avoid unnecessary injections.
I don’t know how correct this is, but I suspect this actually is related to my immune system. MS for example is an autoimmune disease (which is a neurological problem) where certain nerves get attacked and possibly destroyed by our own immune system. I have a feeling my nerves (or my immune system) are hyperactive in some way, and they cause me all these sorts of symptoms.
I haven’t found a cure for the sweating problem. If any of you ever find out what the cause or the cure is, do share with us:)