When diagnosed early even the life threatening malignant melanoma can be treated and cured. Skin cancer of the foot are considered more dangerous because they usually are not diagnosed early. It is very important to understand that every mole on foot are not melanoma, and even if the mole change its color, size it can be harmless. Many factors play role like excess sun exposure, family history, age, race and so so.. if possible can u post a clear picture so we can have a look.

Yes it can happen, melanoma can arise in pre-existing moles, some atypical moles that looks harmless for years can turn into melanoma, so no one can confidently say the moles are harmless, they can turn into melanoma anytime. Being said that, ur race, sun exposure, family history, excess moles and several other factors play an important role. I know everyone worries in such situation, so a better option would be to visit the derma and excise it out and no worries then after.

Try using enough antiperspirant or deodorant to avoid smell bad. Remember to drink lot of water which helps dilutes the concentration of your bodily excrete. There are some prescription preparations that can be given to you by your dermatologist.

Visit your Dermatologist to rule-out any medical condition that might have increase sweating issues in you. Failure to visit the derma on time might result in regrets later.

This kind of nail problem indicates either poor health or bad eating habits that leads to low level of zinc and iron. Besides this there are several other causes like very dry or very wet nails, some nail infections and health issues like anemia and thyroids.  This could be the reason that is causing darkening and cracking of the skin around the nails.

I would suggest you consult dermatologist near you to get checked for thyroids and anemia. Take care of your diet, a diet rich in calcium, proteins, Zine and iron are very helpful. Use moisturizer and avoid harsh chemical and soap.