Chemo isn't easy and everyone reacts differently. You are going through so many emotions and any medication will only confuse these feelings. If the feelings of sadness get worse be sure to seek professional help or find someone you can talk to.
It is so hard to gauge how you will feel with the following chemo treatment but try not to think ahead. Treat each day as it comes.
Depending on how you feel do things that make you happy - but nothing that compromises your immunity. As mentioned above try and drink lots of water to flush out your system.
There is so much good advice on this thread. Good luck