Unlike compartment syndromes, this injury hits you with sudden pain, like a kick in the back of the calf. Trying to rise on tiptoe, let alone walk normally, hurts.
The doctor will certainly find a tender area in the calf, often with a change in density due to the burst blood vessels and formation of a bruise which may sometimes become visible.
These are usually unnecessary, unless the tear is particularly slow to heal.
What else could it be?
There is a long list of possible alternatives, including: stress fractures, muscle pulls and tears, tibial periostitis, nerve and artery entrapment and blockage, referred pain from a lumbar disc, infections, tumours, and pronation syndromes of the foot.
RICE, periodically, for the first 48 hours at least. Later, gradual stretching and strengthening, as with any other muscle injury.
Ultrasound and, in the convalescent stage, massage by a physiotherapist, should restore full, painless movement. The tear should not be surgically drained. Since there is a chance that the damage to the calf could involve myositis ossificans (a formation of bone within a large bruise), treatment should never be over-enthusiastic.
Can you run through it?/Recovery time
One to four weeks, depending on the severity of the tear. The risks of worsening the injury are far greater than any benefit you might obtain from running through it.