Looking for reassurance

Hi everyone, I found a tick on my arm 22nd May and 9 days later started to feel more tired than normal. On 1st June I started doxycycline 200mg a day as a precaution. I had no rash but the tiredness felt stronger. After taking the doxycycline for a couple days, I started to feel much worse (fatigue worsened and muscle aches). I’ve now been on the doxycycline for 13 days and although I have short bursts of feeling almost normal, overall I still have bad fatigue and muscle aches. It’s odd as on Wednesday and Thursday last week I felt as though I was definitely improving, but today and yesterday I am bed bound again. It feels disheartening.

I’m been prescribed doxycycline for 21 days, so I’ve got 8 days left. I have been feeling really anxious about this … I am worried about developing long term symptoms. I’m looking for reassurance or advice on what to do if I still have symptoms after the 21 days. I am UK based. Thank you.