Hi Seria - I do sympathise with your situation but please don't write Spain off because of your first few weeks here. It is a real culture shock and it takes time to get into the ways of the Spanish so try to take it slowiy at first. I've been here 8 months and am still trying to get used to the systems - or lack of them - and need to work hard to keep the blood pressure under control sometimes!
Re your immediate problem - it would seem to me that there are three things you can do - firstly it might be a good idea to go to the town hall and ask if you can stop the doctor opening - I'm not sure of your legal position but there is a lawyer here called Maria de Castro and she gives really good advice on a wide variety of topics - search for her posts and then send her an email. If you have decent Spanish or know someone who does that will make a huge difference if you go to the town hall. The doctor will need permission to develop his underbuild and also will need a licence to use it as a surgery - go and object to the granting of these licences.
Secondly, speak to the Administrator for your community and ask them about the current regulations - they are supposed to advise the President about the law and community regulations.
And thirdly - on a longer term basis - have elections for President and committee for your community and get rid of the present regime. This can be difficult to achieve as you will need to find people to stand for these positions but if you are all upset about the current situation then that should provide motivation - and make sure that anything you want discussed at an Extraordinary General Meeting is formally listed on the agenda as there can be no binding vote taken otherwise.
Your lawyer should have ensured you had your Habitation Certificate before you completed on your property so you should be complaining to them if you still don't have it. Do you have your own electricity and water or are you still on builder's supply? This is really important and you need to keep up the pressure if you don't have this.
You will find the answers to most of your question on this forum. There are lots of us here from Torrevieja and Orihuela Costa so just ask if you need any advice or support.
Best of luck!