Nausea and diarrhoea are listed as side effects of Evorel conti so it is possible, but also may be a coincidence? It's good to increase (oestrogen) gradually as you are doing so perhaps keep on with this just over half a patch and see how it goes. Progestogens can have a sedative effect so this could account for your increased tiredness when you increased the patch. It may be that your body needs time to adjust? The oestrogen level is right when your flushes are eliminated but the progestogen also needs to suit you. I would keep on with it if possible - 3 months is usually the time suggested to try out a new HRT type to see if it works.
Good luck and let us know how you get on - and I hope you feel less tired soon!
Hurrdity x