I have a few concerns about taking SSRIs after consuming big doses of MDMA wich is also a strong SSRIs besides being a serotonin enhancer by reversing the 5HT transporter.
The chanses of serotonin syndrome aren't so high i guess (depending on the doses obviously) but i still wouldn't recomend taking them after such neurologically stressfull experience, it could do some further damage to the serotonin receptors through desensitization.
I would simply take 50-100mg of 5-HTP (let the body deal with its own serotonin), a vitamin complex along with extra antioxidants (vitamin C, lipoic acid, carotenes and melatonin which is excellent for a good refreshing sleep) and some benzos throughout the day to keep you 'cool' and help you relax/sleep (i would personaly go with clonazepam or aprazolam which are pretty long-acting).
I would avoid taking caffeine or the like since it could increase stress levels although i would advice a nice cup of green (or even better white) tea has a lot of antioxydants (olyphenols) with low levels of caffeine plus it has L-theanine wich is good for increasing GABA levels and reduce physical and mental stress.
Something that many people ignore is psychological comforts. Some people normally avoid social interaction because they feel stressed and somehow 'dumb' on 'the day after'. Having comfortable company or getting involved in pleasurable activities helped me a LOT. Never underestimate the self-curing powers of the mind.