Ok this is going to sound silly, but I've forgotten how to run.
I've been injured (knee) for around 2 years now, lots of physio and rehab and in finally starting to run again, today was 2.5min walk, 2.5min jog for 15mins on a treadmill - followed by strength exercises etc.
My problem is, through worry of my knee etc I've been over thinking my technique rather than just running!
If you were running in a perfectly straight line, along a perfectly straight line painted on the floor(or middle of treadmill) where should your feet land? I noticed today that my feet would both land pretty much ON the line, but then I started to think maybe my feet should land EITHER SIDE of the line? That really messed up my running and then neither felt natural ha!
Everybody runs differently. There's even an AI technique called gait recognition that can identify individuals solely based on their unique walking pattern. There's really no definitive right way to run but there are some basics that you want to try and avoid if possible as they are known to cause injury, such as landing with your foot out in front of you or landing with a straight leg.
For example, look at this image:
Looks wrong surely? Almost painful! Well, that's actually Joshua Cheptegi on his way to breaking the 10,000m world record. This is just how he runs and changing this would probably create more issues that it would solve.
What you are describing sounds like leg crossover. Everyone does this naturally to some degree but it can become an issue if the crossover is extreme. There are techniques to correct this and if you want to look into this more there's a couple of videos about it
here and
here.
As you're already running on a treadmill I would suggest you try running barefoot for a few reps. The idea being that it's a lot easier to feel if your form is causing any issues and you should start to naturally correct yourself if it is. You are returning from injury so I would minimise how much you do barefoot as it will put more strain through your body but a treadmill is a lot more forgiving than something like concrete.
Even better would be for a physio to do some gait analysis on you to see if they see any issues that could lead to injury.