I’m guessing it’s not an edible Fig like the trees in this section?

Ficus Benjamina?

Photos would be very helpful. All angles, upclose, etc.

I’m not sure what you mean by putting out sap? Is it the actual white latex sap that Ficus will drip when removing a leaf or is it clear and sticky?

If the latter, it’s not sap. It’s called huneydew and it’s secreted by pests that are feeding on your plant and killing it.

Black spots? Are they pests? Do they move?

You can try spraying with 50/50 water mixed with 70% isopropyl alcohol.

Spray the leaves, stems, every inch of the plant excluding the soil.

You should spray like that every 4 days.

If that doesn’t work, you might want to put the plant outside if it’s still warm enough and throughly spray with something like Bayer 3 in 1 insect disease and mite control.

I wouldn't spray it with anything else until you have a better idea of what is damaging it.

My spraying advice was only if the “sap” was honeydew.