Why do I have swaying/floating feeling after completing 10 day Vipassana course? These sensations and a feeling that my whole body is swaying/floating started on the 7th day of the course. On the 8th day I had quite a surreal experience during one of the group sittings. My eyes would also start watering during meditation. I did share my experience with the assistant teacher and told her that I was scared something was happening to my body. I was also feeling dizzy. The teacher said that this was normal and I should just be aware of these sensations and feelings and not try to control them. The next days until the course ended, I did not pay much attention to the swaying/floating. If I focused on it, I could feel it strongly, otherwise sometimes I would just not be aware of it at all.

My question is that it's been two days that I've been back from the course and the last I meditated was on the morning of the 11th day (final day) of the course. But I still have a swaying/floating feeling. Is this normal? Has anyone experienced this? If yes, what did you do about it and did it stop on its own? After how many days?

Any insight into why this is happening and if its alright to experience this will be appreciated. Thanks!
Yes, it's alright that it's happening (assuming you didn't somehow hurt yourself in an odd way). What you are describing is a normal occurrence at retreats of many varieties, not just Vipassana. They are simply symptoms of prolonged concentration, the degree and type of which are determined by your unique body, mind, and karmic history.

Sensations of lightness, swaying or rocking, tears, tingling, heat, chills, intense joy, bright images, etc. are all common occurences of Piti (also known as Rapture). Piti occurs when a yogi concentrates in the right way for an amount of time. Piti's effects are temporary, and will fade with time, depending on how much and how deeply you experienced it. 

You're having the opposite reaction most have to these things - many yogis get attached to Piti and never go beyond it, or stop going deeper because they think they've reached Nibbana. So you're ahead of the curve in knowing that these pleasures are also Dukkha. You're having an anxious reaction to it, which in turn causes additional problems like trouble sleeping, which in turn causes more anxiety, panic, and stress in an endless feedback loop. What we resist, persists. Surrender.

I've personally experienced what you're describing many times. It will pass. You may also be experiencing a new, deeper awareness of your body that you haven't had before. Your mind is now more clear, focused, and observant - it's no wonder you're experiencing new strange things. That's pretty neat! A shift in perspective may be all that you really need.

Your feeling of lightness may be akin to the early stages of what is described in the suttas and by monks as the power of levitation. ;) Just try to let go, stop worrying, and enjoy these new things for now. Get back on the meditation cushion. Observe them just like any other meditation object, investigate them. Where exactly is the sensation? What makes it so insufferable, in terms of experience? Does it have an essence? Does it change? When does judgement arise, before or after the sensation?

Hope you feel better, find peace, and liberate yourself from this suffering.