Go and see a sports med doctor and have a RPP injection into the elbow guided by an ultrasound machine.
The ultrasound will show the tears in the tendon the PRP will heal the tendon as it requires collagen to heal the tears which the PRP will do.
Will take about two months to heal with stretching and strengthening exercises.
Cost is around 300.00

Maybe depends on how big the tear in the tendon is on the elbow sometimes it's not enough as there is limited blood flow to help heal the tendon hence why PRP does the trick.
It's certainly worked for me but do your own research the fact I am and electrician plus I wing and kite I have experienced tennis elbow on both arms and PRP has healed both elbows from tennis elbow for me.