I know it sounds silly, since you're just walking around, but have you tried trekking poles? They make you use your whole body and take pressure off your knees. That plus a knee sleeve has really helped for backpacking guides I've worked with.

Light bracing may help, like an athletic brace that's made to move in. If you have access to it a stationary bike or a row machine are both good ways to do cardio with no joint strain.

Congrats on being down 20 comrade! I think that as far as exercising goes, walking should get easier and easier on your joints as you lose more weight and gain more muscle in your legs to compensate for the pressure on your knees right now. It makes sense if you’re just starting out that they might be giving you some trouble, but i think a doctor would probably assure you that walking is still overall a good low impact form of exercise despite the joint issues you’re having. Listen to your body and if you’re feeling a lot of pain I would go easy on them and try other exercises that are even lower impact but ultimately it’s something that your body will learn to adjust to. Not a doctor but I do have joint issues as well and I find that just starting out any type of exercise feels tougher on my joints than it does once I’ve got some muscle built up.

Just to add to what everyone else has said, if you don't foam roll there's a link to make your own in the sidebar (or you can pick one up at a goodwill usually now or new at any like big box sporting goods shop) and can try rolling out your legs before and after you walk at least.

A lot of times (anecdotally) clients that had clicking had it go away after rolling and stretching routines.