I'd check to see if any of my Govenors have died in the Plague. Have they? Did you appoint new Govenors? Compare the Acumen of the old and new Govenors. If the new have lower Acumen then you'll suffer a loss of income. In any event, try see that your Govenors have at least 4 acumen.

Regarding the blockade, did you have a Trade Network and were you receiving income from Trade? Just a single enemy ship can ruin your Trade Network.

Also, has the number of troops increased substantially?? JFYI, 2000 Florins is pretty borderline in terms of income and can easily turn into deficit in a single turn.

Lastly, don't forget to peruse the TOC.

Good Luck Have Fun