BASED on the information provided it seem like one of the complication like "RUPTURE TENDON" of the muscle that gets inserted at the elbow joint.
****(1) TENNIS ELBOW
is an kind of swelling which occurs due to repeated used of the joint for doing harsh stroke
, like playing tennis , cricket , baseball / golf. Now the basic treatment is to stop playing for a while till the swelling regresses to normal , for faster healing steroid
injection are placed into the joint.
****(2) Now about the "PAIN that is extending to the FOREARM" - their is a nerve called radial nerve
that passes very closed to the insertion on the muscle's tendon (tail end of muscle which thin and fibrous) that gets compressed by one or the other mean and can lead to the pain in the forearm.
****(3) NOW " MISSING CHUNK/TISSUE " - the missing chunk / tissue mostly a ruptured tendon that is pulled on to other side where its stilled attached leaving a space where it rupture.
Consult ORTHOPEDIC SURGEON- talk about what happened and follow his/her directives
here is mostly they will do
1) Physical exam
of the joint to see rupture/ another underlying issues
3) will give you pain reliever ,
4) may need to do minor surgery to fix tendon
Hope it helps.