tumors do not grow in 3 weeks. how long does it take for tumors to grow? usually years.
yes, swelling would show on a CT, but it obviously didnt.
re your left eye "feeling hard"...if you had an eye exam and everything was fine, then you are fine. it doesnt mean anything.
um, no. 2mm is probably not enough to demand that your insurance company pay for an MRI.
what are the guidelines? who knows? depends on your:
1) presentation
2) insurance company
3) doctor(s)
yes, if they did a CT b/c you were complaining of a difference between your 2 eyes, then we have to assume they paid close attention to your orbit.
you probably need thyroid testing 1st to rule out grave's disease.
if thats negative, then your next step will be neuro & MRI.
this will be a lengthy process b/c getting a "non-emergent" MRI takes forever. months sometimes, depending on where you live. plus you might end up arguing with your docs & insurance company over whether or not you need an MRI. MRI's are really expensive and an insurance company is not going to pay for one just b/c you think there's a difference in appearance between your 2 eyes. some doc somehwere is going to have to order you an MRI and have a good reason for doing it, which so far you do not have a good reason.
good luck. try not to get too frustrated "waiting for these doctors"...b/c i fear that you have a LOT of waiting still ahead of you.