All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
This matter depends on the instruction of a trusted Muslim doctor, so you should consult a trustworthy Muslim doctor about this matter. If he determines that water is harmful to you, then there is no harm on you for performing Tayammum (dry ablution) in this case, and if he determines that water does not harm you, then you must wash.
The doctor should examine you and diagnose your disease and you should not rely just on listening to what people say because cases may differ about the same disease, so the ruling on one case may be different from another. One should not rely on what people say or on the experience of another person whose condition may be different from yours. In conclusion, you must consult a trusted Muslim doctor about your case and act according to his advice in this regard.
Allah knows best.