Hello dear, It could be a complete tear of your muscle. Because in complete tear (grade-3) pain may not be there. but your movement must be affected. It would be difficult for you to move your wrist and forearm. If it is not then physical examination is required to rule out the cause of swelling. So just have some patience and wait for your ultrasound
report to come. Then it will be clear about the injury
and swelling. Then only appropriate management can be decided. for the timing you can use one fore arm sleeve or crape and keep your forearm elevated to minimise the swelling. you can do some finger gripping exercises if possible. Wish you a good health..