You are experiencing unpleasant and not so rare symptoms of a healing crisis. Vomiting ASAP would help you a lot.
Additionally, if an idea of an enema is not foreign to you, you could do it to bring much comfort to your suffering body.
The most important thing is NOT to give up at this stage because you could experience discomfort for quite a long time after starting re-feeding. Always start re-feeding when feeling good.