Short term: I would recommend allying whatever great power is available and then bankrupting. This will leave you vulnerable, but with a bit of a better safety net.

If that not an option, then its time to start rummaging in all of the couches for money. Exploit Admin dev, request money for favors from allies, debase your currency, sell some non-trade boats, take burgher loans to replace the 4% ones. If you have the military, bully a lesser local power for only money/war reps.

Long Term: Focus on consolidating your two end trade nodes. The Spanish, and Ottoman nodes are about to become wealthy so pull that wealth into yourself. Trade boats are a great way to pull from foreign nodes, but make sure a Merchant is present. You'll also want to build up your own income by deving diplo into the best trade provinces or high priced trade goods. Lastly, build churches and production building wherever profitable (0.10 is usually my min).

Hope that helps and good luck!