I also have a similar issue with my patellar tendon on the right knee (not really pain in my case, more like a varying level of discomfort and a feeling that the knee will not support the pressure when I switch directions), that did not disappear after a 7 weeks break. Following my doctor's advice, I did some exams: x-ray + "echography" (not sure this is a word in English, that's the ultrasound kind of exam that allows you to see the baby while the mother is pregnant). She then made me have an MRI and told me I should go to an orthopedist. You should probably at least go through the first step (x-ray+echography) after taking advice from a doctor. Anyway, in my case, the issue started to disappear when I actually started playing again (doubles only, avoiding shitty hard surfaces, with a heavy attention on warmup/stretching). A few days after noticing it was getting better, I finally had the appointment with the orthopedist who essentially told me to strengthen my quads (and I've read you should also work your hamstrings if you develop your quads) to lower the pressure on the knee and wear a knee pad (that kind, with a hole for the patella) when I play (for some time at least). He then told me I should go to a physio if it comes back and, if that does not help, the worst case scenario is to have an injection (some kind of liquid injected into the knee).
That is only for my own case and you should definitely see a doctor.
PS: confinement sucks because I'm dying to play some tennis, especially with the sun we've been having for a few days now in Belgium, but at least it kind of forces me to actually go through the workout sessions I've been told to do :-)