What Causes Decreased Appetite Along With Stiff Neck While On Doxycycline?

Hi, I m a 35 year old male who is on a long term treatment of doxycycline as a prevention for reoccurring chalazions. it is a 6 week treatment - 100mg a day for first 3 weeks and 50mg a day for the second 3 weeks. I am now on week 5, taking 50 mg a day. For the past week, I ve had a stiff neck (mild to moderate), which I at first brushed off as stress related. I ve also notice a mild decrease in appetite for the past couple of weeks. Normally these symptoms would not worry me too much, however I m a bit apprehensive about being on long term antibiotics. If these symptoms are caused by the doxycycline can I expect them to stop when I stop the treatment? And are these symptoms cause for concern? I plan to make an appointment with my GP but thought I d ask the question here. thank you.