Both Of My Achillies Tendons Are Burning. The Burning Sensations

Both of my achillies tendons are burning. The burning sensations sometimes travels upwards about two inches. The burning sensations started originally on my left tendon, then started on my right tendon. The burning usually occurs on(in) one tendon at a time, rarely occurs in both at the same time but has happened. Short rests off of my feet help the sensations go away, but short breaks are only a temporary relief. I am not a diabetic. I am a very active person and this has altered my life greatly. What could this be and what can I do for this condition? Thank you for any help.