Hello,
On the extensive list of side effects for amoxicillin, anxiety is list. This may be causing mood swings. If you did a trial of not taking it for a week and felt noticeably better - I would talk to your doctor again and get off the stuff. The way you are feeling and your symptoms are the most important diagnostic tool.
I didn't know this was still allowed. Are you in the US? When I was young, they used antibiotics to treat acne. Here's what happens: even a short course of antibiotics not only kills off harmful bacteria, it also kills off beneficial bacteria. Beneficial bacteria are not only an essential part of your immune system keeping you safe from things a whole lot more harmful to you that having a less than ideal appearance. Taking them as long as you have can leave you with chronic yeast infections, chronic fatigue syndrome, drug-resistant bacteria causing any number of diseases, fibromyalgia, and, yes, mental problems. Our beneficial organisms are partly responsible for our mental health and are one of the biggest current areas of research for helping people with anxiety and depression. They help manufacture some of our B vitamins, essential for proper mood, and reduce the inflammation that many believe to be a large factor in mental health as well as Alzheimer's prevention. Because of this, the CDC and FDA have both cracked down on doctors to stop prescribing antibiotics for things that don't kill us, such as most sinus infections, ear infections, and, of course, acne. I don't know how old you are, but if you're young, this will pass in time. You'll just stop getting acne some day. Some people have certain conditions that make acne more likely, but there are ways to try and deal with it that doesn't involve antibiotics. There are many plant medicines and amino acids that help some people, and of course keeping your skin clean and avoiding toxic chemicals such as petroleum based products that block your pores helps. Diet can be completely healing. There's no question antibiotics work for this in the short term, but by increasing long-term inflammation and reducing the effectiveness of your immune system you have to ask if the trade-off is worth it. Maybe for you it is. I wouldn't do it again knowing what we now know about antibiotics. And yes, it can affect mental health adversely.