I loved teaching. I totally threw myself into it. I managed the school choir, the chess club and cross-country running, I produced shows and I was a member of the Parent Teacher Association for seven years.

The first signs of stress emerged when I had my first Ofsted inspection. I was not fazed during it and got a decent report, but afterwards I was knocked down by anxiety.

The stress-induced panic attacks were the worst. I had terrible chest pains and hyperventilated. I just had to get back home as quickly as possible.

I was off for about a week. When I went back to school, I could not be within three feet of a child without feeling anxious. It was not the pupils’ fault: it is just how the anxiety manifested itself.

It got to the stage where even the thought of an observation had me in fits of panic. A woman from the local authority started to observe lessons and she was terribly picky. She sat in on an hour-long maths lesson, but her only feedback was on about two minutes in the middle, which she thought lacked pace.

A new headteacher arrived who I did not get on with. After his first observation of my class, he said it was only “satisfactory”. I thought satisfactory was the benchmark, but clearly it was no longer good enough.

I then got a letter in my pigeon-hole saying he would observe me every week. It felt like he was trying to get rid of me.

It got a lot worse from there. I had a course one afternoon and the head was going to cover for me. Just the thought of him rubbishing my plans got me so upset. I sat in my classroom, crying and shaking uncontrollably. I felt I was losing it.

On other occasions, the head would sit at the back of the room with a clipboard and make constant notes throughout the lesson. His only feedback seemed to be negative. I felt I only had to look in the wrong direction and I would be criticised. I couldn’t be myself.

I was told about a maths lesson observation three weeks in advance and prepared for nothing else. I followed my long-term plans meticulously. My professional instincts told me to make changes because the pupils had already covered the material, but I was frightened in case I was criticised for doing so.

The lesson was not bad, but the pupils did not learn anything new. The head gave me fours - a failing lesson.

I had been teaching part-time, but now the head reduced my role to cover duties. He said he did it for me, but it felt like a demotion. It was terribly demoralising.

I hit rock-bottom and felt I was nearing a breakdown. At the beginning of last year, he observed an RE lesson of mine - I had been taken off the core subjects - and never gave me any feedback.

Every time I saw him, I felt anxious. I did not know what he thought and could not draw a line under it. When I asked, he said he would catch up with me sometime. He never did.

I ended up taking it out on a child, calling her a “spoilt little brat”. I knew I shouldn’t have done it.

The head was not the least bit interested in why I had shouted at the girl. Instead, he said that if Ofsted had been in, this incident could have led to us being labelled a failing school.

I went off on the Easter break and could not return at the end of it. I went to my doctor and physically shook. I realised I was making myself ill, that I was living on a knife-edge.

I have now left teaching and have a part-time job working for a charity. I’m relieved but also upset. I was at the school for 16 years - three times as long as the head - and feel I was edged out by him. I am convinced that if he had better people-management skills, I would not have found observations so stressful.

As told to Hannah Frankel. If you have an experience to share, email features@tes.co.uk.