It could also be iron defiency anaemia. Initially, I displayed the same symptoms you are experiencing and thought that I had a Thyroid problem. However, my blood sample came back showing that I had an iron deficiency. I was diagnosed with this after having problems retaining information. This was actually noticed by the practice educator I had been shadowing, who commented to my placement coordinator about my memory. My other symptoms included:always being cold (particularly my feet), hair loss, insomnia, nails spliiting at the sides, palpitations (heart missing beats), retaining information, concentration, exhaustion and and my anxiety levels also increased.
You would be better visiting your GP and describe your symtoms to them. They should offer to take blood samples to be sent off for testing. If they don't, you should ask for them to do some blood tests to rule anything out.