Spotting on the leaves can be due to fungal or bacterial diseases, as well as aphids, or even over/under-watering. Aphids would be easy to detect as they are visible. If it is due to a disease, your best approach is to remove the affected leaves. Martha Washington geraniums are much more difficult to re-bloom than the common bedding geranium. They need roughly 6 weeks of 40-50 degrees F. to initiate flower buds. This is difficult to attain in most homes. However, you can still grow it as a foliage plant, keeping it in the bright light that you have. Let the soil dry out slightly before watering.