Eating 1200 calories and not losing weight

Have you talked to the doctor about your weight? My guess is that you've got some fluid retention because of the other medical condition, and that's hiding your weight loss. Ask the doctor if that's likely, and if so, weigh yourself less often. If you have these treatments on a schedule, you could make your weigh-in a certain number of days after each treatment and compare those weights. Or, the doctor might ask you to monitor your weight to help determine how your treatment is going.

Of COURSE your back and head are hurting, they drained a significant amount of cerebrospinal fluid from you! A headache is a pretty common side effect after a lumbar puncture.

I agree with the coach. No exercise until you see your doctor and check in with his office that the headache and back pain should still be present. You might also consider eating a little more to replenish your body's resources faster, but again, please talk to your doctor.

I concur. Doctor to eval/treat before any activity not cleared by your MD or PT.
What is your daily menu?

I am not a doctor, but I don't think you are getting the proper nutrition for your body at 1200 calories a day. The first 2 weeks of following this probably shocked your body into losing but you probably also lost muscle, which actually helps you burn more calories. You should always follow what your doctor suggests, especially if you have any health concerns.
When your body doesn't get what it needs, it goes into 'starvation' mode and your metabolism slows down, so you would need to eat fewer and fewer calories in order to keep up that kind of loss. But that is not healthy and of course you could not maintain that for any length of time without having serious health problems.

Why are you eating only 1200 calories?

At your weight, that may be too little. Given your health issues, I would suggest talking with your doctor to get a registered dietician, and find something appropriate for your needs. If you don't eat enough to support your body's needs, it can slow your metabolism, and sabotage your weight loss efforts.

I agree that you need to return to your doctor for follow before any exercise is planned. Illness, inflammation, IV fluids, medicaion can all alter your fluid status and the number on the scales. Talk to your doctor about all this.
SP Dietitian Becky

During the first week or two I lost about 5 lbs. It's been almost a month since then and my weight has gone up a couple of lbs then back down a couple of lbs, and so on, so forth. Doesn't seem like I'm really losing anything. Not even a lb a week.

On Saturday I had to go to the hospital because of a serious condition (pseudotumor cerebri), I had two lumbar punctures where they drained 70 ccs of cerebrospinal fluid and since then, my back and head have started hurting. I get dizzy a lot and I'm constantly tired. I don't think it's such a good idea for me to go to the gym until I see my doctor on Monday. But before that I went for walks almost every day, and even sedentary shouldn't I be losing a lb a week at 1200 calories a day?

Just to be clear, I weigh 257 and I'm 5'.