What are your most recent thyroid labs? That may help with understanding your situation better.
Along with your most recent thyroid labs, be sure to include reference ranges, which vary lab to lab and have to come from your own report.
Have you considered peri-menopause as a source for the night sweats/hot flashes? I had those horribly, when I was in peri-menopause, to the point where I sometimes had to get up and change sheets, shower and put on clean night clothes.
B-12 deficiency can cause the zombie fatigue, but if you're taking daily shots (very rare), that should be resolving (depending on how long you've been on the shots).
Some of the weight gain, could be attributable to constipation.
Muscle spasms/cramps are often caused from dehydration or an electrolyte imbalance. I, sometimes, have to take extra potassium for muscle cramps. I get them, mainly in my toes and fingers, but also in my neck, back and sometimes, lower chest. About a year and half ago, I was put on gabapentin for neuropathy caused by years of untreated Pernicious Anemia and that pretty well controlled the muscle cramps, as well. My neuro seemed to think they might have been related to the long standing B-12 deficiency. I was recently switched from the gabapentin to Topiramate, because of weight gain caused by the gaba and I've been having more of the toe cramps again. If they get much worse, I will request to be put back on the gabapentin, regardless of the weight issue.
Once we see your thyroid labs, we'll be able to add more comments.
Labs done 5/20/14
TSH 3.03 (range .40-4.50)
Free t4 1.4 (range .8-1.8)
Anti-TPO <1 (range <9
Calcium 8.8 (range 8.6-10.2)
Potassium 4.2 ( range 3.5-5.3)
Sodium 139 (range 135-146)
ANA screen negative
Still awaiting free T3 , PTH, magnesium and phosphorus results done last week
I have been doing the b12 shots for 7 years now. Usually 2ml monthly but when labs show low levels then I go to shots daily for 10 days, then weekly for 4 weeks and back to monthly based on where the updated lab results are. All the symptoms I've been having for years, except the body temp issues. Last night I had goosebumps sitting outside in 86 degree weather and I can be sweating from my head to legs in air conditioning. The nughtsweats has been limited to a few times over the past 7 years but as of this week, it has been every night. I am nauseous almost always and vomit quite a bit, with little appetite so the rapid weight gain in such a short period of time is odd. Thank you for your responses!
I take 2000 mcg of sublingual B12 spray daily for autoimmune pernicious anaemia and have done so for over 5 years. So happy to not have to inject needles. I could not go a month without B12!! Crazy talk. I'm seeing symptoms show up very soon after stopping B12.
TSH is a bit high. Calcium serum looks too low. Try the chvostek sign (youtube demo on youtube). This is my slam dunk sign of calcium deficiency.
Typically, injected B-12 stays in the system much longer than other delivery methods, which is why it's most often prescribed for Pernicious Anemia.
I agree that TSH is a tad on the high side, but FT4 is at 60%, so that doesn't indicate hypo, unless you aren't converting FT4 to FT3... You should try to get your doctor to test FT3.
You have the TPOab, but what about Thyroglobulin Antibodies (TgAb)? Those also need to be done in order to rule out Hashimoto's. They are both markers for it.