Hi, My Son Is In Despair As He Has Been

Hi, my son is in despair as he has been suffering for some time and the GP is not helping. He has very painful muscles in his feet from the heel to the toes. He is at a stage now where he can bearly walk well enough to get to work and is seriously at risk of losing his job now due to this. This started with very severe sweeting of the feet and painful redness and inflammation of the skin. GP treated with a foot soak and creams and this has improved a bit, but the muscle pain is unbearable. He is also getting rashes, spots and puss filled leisions on scalp, face and upper arms and other areas of the body. His teeth have also become very bad despite good oral hygiene. In addition he is feeling fatigued and very depressed. He has had most common blood tests which have been 'normal'. The GP now can only advise pain killers and rest but this is no option or cure and my son feels that his life is over. Please help.