Sorry to hear that you're suffering Barry, I would recommend you get a full blood test done, then with that results, go to one of the well known Hospitals to see a doctor.
Best go to jib store, pic your own components or tell them what it needs to do. Eg office or games. Google best gaming pc and works down to match budget. Wouldn't trust pc from China, simply not possible to address any issues.
Make sure you have the paperwork signed by previous owner - if it's too much hassle to change into your name - just keep it in previous name till you sell or store it.
Immigration are definitely the best to ask, but for your own security I would definitely get the father to sign a standard legal document ASAP - he is liable if you push 4childsupport. really don't think it's expensive.
If things are in your way - be very apologetic when moving them - apologies for needing to pass, they appreciate respect from anyone, it will get you the response needed. Frustrating to some but to disregard this culture is at your own peril. Just saying.