About a month ago i started to notice a slight pain in the front of my left shin after i ran. It didnt hurt when i was actually running so i didnt think much more of it.
Now, the muscle behind the shin is agony. I cant run or even walk comfortably and when i stop the pain increases and the muscle stiffens right up. It hurts to put any pressure on the muscle and if i press the back of the leg, i feel the pain in the front of the leg aswell.
Could anyone please shed some light on this injury and what is the best form of action to take.

hopefully things are improving,but there are a number of possibile causes of your pain:i)rather than the gastroc it maybe your tibialis posterior;this can become inflamed due to excessive pronation;it lies deep to the gastrocnemius and runs on the inside of the shin to insert into the side of the foot;maybe your trainers have lost some support? or increase in mileage?or change of terrain? ice at least 3xday and relative rest ie cycling/water running if poss ii) if it was the gastroc prob better by now as it has great blood supply and heals well;if still painfull again ice and a good deep massage(tranversely accross muscle)at least 10 mins daily plus calf stretch(pushing wall over one)but raise your foot more on little toe side with book/brick so the stretch is felt more on inside of calf iii) one other poss is not muscle at all but a nerve thats been irritated (not as bad as it sounds). if i were you id 1) take a course of ibuprofen(assuming your not asthmatic,on BP meds or have gut probs),2)ice the area regularly,3) stretch as discomfort allows(holding at least 10 secs)4)reduce mileage/xtrain,5)check out your trainers....hope this is of use to you