It is very important to feel valued in any job role.
Firstly, you may wish to look at your own behaviour - and ask yourself if any of their criticism is really true - is Head Office simply doing their job by chasing up sick notes, reasons for absences etc???
Whilst it may seem like people are harassing you, it may just be that they have targets to meet - paperwork to complete, that sort of thing, to ensure the correct procedures are followed. It is necessary these days to cover their own backs, what with people sueing for stress on the job and not being 'looked out for' etc.
If this is not the case and you are genuinely unhappy, try talking to your line-manager about how you feel - they should try to help and may not be aware of any problems. They MAY assume you're just being grumpy and awkward but when they see you are genuinely concerned about your position, i'm sure they will do their best to help. Good luck