Body ache, leg pain. Having right now.

My father is suffering from Body ache, leg pain and burning sensation in foot jaw. Sometime he told us i don't have power to stand on my legs and i don't have senses what is going with me. In hindi- mere mai himmat nahi hai and pau mai se aag nikal rahi hai. Even he stop eating food during this period. It happens once every 2 weeks and last for 2-3 days and then after it automatically feels normal for next 2 weeks. It is regular from last 5-6 years and consult couple of general physician and done all the test and everytime test are normal. My father having thyroid and BP problem. Chain smoker and quite drink from last 4 yrs and was heavy drinker. Could you please suggest what need to be done in this case and shall i continue with the medicines which my dad is having right now.