How much to treat malnutrition? What will I need?
All in all, £55 -60 obtained and spent solely on food at this point, would stop malnutrition in its tracks, get you through crisis back to health, and get you ready for a week building up once symptoms have gone. You can shave money off all corners of that, and with a willingness to deal with monotony, override your tastebuds, and a bit of time scooting between shops and the internet, could probably shave a good £15-20 off that, but every penny you can muster here you should use. If you can go over £55, if your mum or dad or a friend will help you out, you can sell something that will raise that or more, it warrants as that kind of emergency= this is a much more pleasant and effective process with variety.
This is not a case of budgeting, this is case of sweeping everything possible off your priority list so you can spend that money on food while you deal with your symptoms and recover. You will quickly come to a point where you are back at a more manageable and budgetable level very quickly, but for the best part of a week you NEED there to be food that meets your nutritional needs without interruption, and you should ideally be aiming to do this over a couple of weeks. You will NOT need to spend this much on food every week, this is purely to treat your malnutrition.
If you don’t address it now, you are putting the day off when you do have to address it. Not for long, it will get worse, and the financial climate is getting worse. It won’t go away, and you will get less warning and it will strike you when you are at your lowest and under stress, you will get ill or something will try to pack in. You are no good dead. You are very seriously ill and could do lasting damage. This is time for holding your nerve, you will feel so radically different when you have addressed this, you will not regret it.