What if somebody will make a huge dump and sell it all the way to earn some profits because of this rally in bitcoin,and someone sees it and do that same thing. Is there any effect on bitcoin when someone to this,?
It would depend if those "somebody" holds a lot of Bitcoins. Just remember what the Bitfinex hack has caused us. We were slowly increasing and then it stopped and dropped really hard. Right now, we're still recovering from that.
Its better not to get panic when price drops, we need to have faith in the ability of bitcoins, as it has fallen many times in the past but again we saw major rise in the price of bitcoin.
whenever there is a fall you have to look for the reasons of that fall and see the size of it too. for example there are always a lot of small drops in bitcoin ($20 or so) and all these are normal for bitcoin and then again there are bigger drops that for example there was the hack drop which caused a panic.
if you find the reason for the drop then you can decide to go in or not.