Hi FireFox,
You may have described the most likely cause here.
It may be worthy trying a different pillow because the gap between your head and the pillow may have changed with a different mattress so your memory foam pillow may no longer suitable to keep your head and neck in good alignment and in combination with the pressure of your chin on your hands is impairing circulation.
Some of the suggestions in posts #2 and #3 here may also be helpful.
The only reliable way to know is to try it because there are too many unknowns and variables involved to predict whether any mattress will work for you with any certainty and other people’'s experience on a mattress may be very different from your own. Either it will work and of course you would be happy or it doesn’t and like the Casper it also has a great return policy so there would be little risk in trying it outside of the time and effort involved in testing it out and returning or donating it and starting over again … but I would experiment with your pillow first because if I had to guess either your pillow and/or your posture is the most likely cause.
Phoenix