Hello @klaubi
I am very familiar with coscochondritis!! Uhh brings back horrible memories of the most horrific pain I ever thought I would have to endure!!

How long have you had the symptoms?? Have you tried physical therapy? Please discuss the use of a TENS unit with your doctor before attempting it. It is dangerous to do near the heart and since it is your chest wall pain you are trying to releave they may not want you to use it.
Here is some information on your condition and some treatment options. https://www.mayoclinic.org/diseases-conditions/costochondritis/symptoms-causes/syc-20371175

Mayo Clinic treated me for my costochondral coscochondritis. After exhausting all (and I mean ALL) treatment options I ended up getting Fluoroscopy guided injections through the sternal manubrium joint to relieve my pain.

Prayers for pain relief!!
Dawn