TSH normally decreases with treatment, however it's possible that you have Hashimoto's (an autoimmune condition which is the most prevalent cause of hypothyroidism). With Hashimoto's TSH levels do tend to fluctuate, mine fluctated from 12 to 20 in just a week when I first started treatment. Once optimally medicated it should stay lower, however fluctuations can continue to happen, and it can be a bit tricky to find a constant dose in such a case.
If you haven't yet been tested for Hashimoto's you should. Ask your doctor to test for thyroid antibodies, if antibodies are above range on the results then Hashimoto's is diagnosed.
You will likely be given a dosage increase on your next visit. Usually with each dose adjustment it takes about 4 weeks to really feel the effect, and often you can feel better then worse (if the dosage isn't high enough yet). Only once on the optimal dosage do symptoms tend to subside.
Always take your thyroid medication on an empty stomach, with a full glass of water, and away from other medications. Rule if thumb is not to eat one hour before or two hours after taking the pill. And space at least 4 hours away from other meds and supplements. Some people take it first thing in the morning, others take it at night, some even in the middle of the night. What matters most is to find a schedule that works for you and stick to it, rather than taking the tablet at random times each day.
For your next test your doctor will likely do TSH and FT4, what would be good is if they can also do FT3 test and antibody tests. Plus the vitamins I previously mentioned. If you're unable to get all these tests done it is possible to do them privately, but maybe your doctor will be nice enough that you can avoid that route.
Regarding Shelcon 500 I don't really know anything about them. What is this medication used for?