Which coins haven't had dumps in the past few weeks? Almost all have except for the top coins, well some of them have lost value as well. GTM should be fine once people stop fomoing into BTC, gin also has taken a hit so its not just GTM. In the long term we should see GTM do well as there is a lot more to come in the future.
This is exactly what happened in general recent weeks. Bitcoin continuously has kept climbing, so altcoins have all gradually dumped in BTC pairs, not only Gentarium. Such patterns lasted for weeks, so I believe that this will end soon, and someday (soon) bitcoin and altcoins will move in same directions (upwards/ downwards, it depends on specific period). I wish that they will both moving upwards together first before moving the same in downwards.