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 or other exacerbating activity) for a while.

After the acute period, heat may be beneficial – as long as you aren’t acutely re-activiating the original insult, heat mayy be ok. As with anything, if you try it a couple of times and it makes symptoms worse – stop.

Inflammation has one consistent quality – the longer you have it, the longer it takes to resolve. My best advice is to get a plan of attack you are comfortable with trying, – which in this case may require the expertise of a new doc, and go with it. Look for a plan that focuses on getting you symptom free for increasing periods of time with less and less intervention.

Also, a fresh look at your symptoms and exam may lead to a more refined diagnosis. Lots of stuff, I know, but the complexities of the human body, deserve complex thought and attention.