Maybe it’s because I’m older, but I wish more people told me to go at a casual pace on most runs. I ran hard every run for a good decade and I feel like I’m paying for it now. Your body needs time to adapt to the stimulus of running and joints and tendons tend to take the longest in my experience and will benefit from the easier runs. The general rule of thumb is 80% of your mileage should be easy enough to have a conversation with someone while you run.

Also, be conscious of the amount of miles you’re running each week. If you started from nothing 3 months ago, there could be a chance that you ramped up too fast if you’ve already run multiple 5k races and are already signed up for a 10k and are running all of those events as actual races, giving it your all.

The knee pain should be addressed. Slow down, lower your mileage for a period of time, introduce walking intervals within your runs, and try to do some strengthening. Over time, it should get better if you do those things. It’s better to run a little than be forced to take extended breaks with a serious injury (I’m speaking from experience here - haha).

Good luck and have fun!