you didn't mentioned how old are you. The combination of symptoms which you are having can stem from one illness or may be here we are dealing with multiple problems.
and random fast beat need to be investigated. I suggest basis test .ETT.24 hour holter,full blood count blood test
for urea,sodium,potassium,creatinne,clcium and thyroid
2.fatigue ,hot flushes could be part of post menopausal syndrome if you are in that age group.
3.Best strategy is to rule out heart disease
first the we can tackle other issues.