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Don't worry too much but we are surprised if symptoms appear again. As our body gets used to a dose of levothyroxine, which is usually gradually increased symptoms can develop again. As @greygoose suggests you probably need an increase in dose.
Blood tests should always be at the very earliest possible, fasting (you can drink water) and allow a gap of 24hours between your last dose of levo at the test and take afterwards. This allows our TSH to be at it's highest as GPs are apt to adjust dose unnecessarily according to the TSH.
We have to read, learn and ask questions and always get a print-out of results with the ranges for our own records and you can post if you have a query. Ranges are important as labs differ too.
Also ask GP to test B12, Vit D, iron, ferritin and folate as we can be deficient which can also cause symptoms.
Levothyroxine is taken first thing with one full glass of water and wait about an hour before eating.