Early on start with ice to the affected area (off and on when you can for 48 to 72 hours after the onset of problems. Acute swelling can be worsened by heat.
Rest (no tennis) for a while.
After the acute period, heat may be beneficial.
Throughout, antiinflammatory meds like advil – if you can take these – are helpful as well.
When back to tennis – test the waters. If aggravated, re-ice and take more time. Good Luck
Rest, hot compresses to the area, Deep Heat rub. There’s also Cortizone shots to the area by doctors.