Edema on the forearm

Good afternoon!
After trenirovki in the junior gym the next day in the morning there was a strong swelling of the left forearm and elbow. Pain and some uncomfortable sensations do not feel except pressure inside the hand.
After the visit to the traumatologist, nothing could be found. Have registered to smear a hand with LIaton. Neither X-ray nor blood test nor ultrasound of veins revealed anything.
During the training of strong loads onthe forearm was not, the traning was on the muscles of the chest and back, so I'm not sure that the edema is associated with physical exertion. Trauma preceded edema was not. The next day, the swelling was slightly slept, but after that 2 days remains unchanged. The doctor said to come in a week.

Please specify, with what else may be associated with edema and for how long can physical activity be contraindicated. Is it possible to visit the sauna?