When bitcoin price is going in a downward trend what's the best way to weather the storm?
Best way is wait for the storm to be over, its not likely gonna kill bitcoin, the downtrend of bitcoin and alt coin is nothing new in the past years this was always happening.
get out while you still can?
Nope, getting out and selling your bitcoin and trading it to fiat is a bad move, you should just wait because bitcoin will break even or get its price rise again.
Buy alt coins?
Could be an option but regarding what coin is the problem, there may seem promising alt coin but who knows it might fall just right after you bought one.
or just wait it out?
Waiting would be the best solution when it comes to bitcoin, there are many people who just patiently waiting for bitcoin to have a high price again and would probably sell all their bitcoin.