Hi Fahim
This doesn’t sound to me a straight forward muscle tear. It is a bit hard to really know is going on in an internet conversation. However I suspect you may have done something to cause abnormal nerve tension in one of the components of the brachial plexus. This is based on:

*The symptoms came on immediately after the injurious activity and not during it. Usually if you tear a muscle or tendon you feel something during the activity.

*The symptoms seem very irritable – stirred up for a whole week is a long time of aggravation. Neural tissue is often much more irritable like this.

*The more diffuse nature of the symptoms could be explained by adverse neural tension

*The two exercises you describe that stir up the pain both would put the brachial plexus or components of it on stretch and this would explain why you are so saw after it. If this is true most likely the lateral raises are particularly aggravating.

Do you have any tingling or loss of feeling anywhere in the limb? If you do this adds weight to this diagnosis although even if you don’t it could still be due to adverse neural tension.

As you are interested in continuing your weights program I think it would be a good idea to get some advice from a specialist musculoskeletal physio who can work with you. If you do have neural problem this can take quite a long time to settle down and you may really need some help with your rehab. Nothing will be achieved by "working through" the pain. You will just make your self really sore and could potentially make matters worse.

In the mean time avoid anything that stirs up the pain. Exercises that involve elevating or abducting the arms should be avoided , particularly with an extended elbow.

Things like preacher curls, dips may be ok and backward rows may be ok as long as you don’t start in too much shoulder flexion or with elbows completely extended. However the rule is anything that stirs up the pain should be avoided. The raises you describe, bench press, Pec deck would definitely be out.