The symptoms on your Pawpaw (Papaya) are related to nutrient deficiencies.
In commercial Papaya plantations, fertilizer is usually applied 2–4 times per year. In the home garden, the addition of 1/4 cup of a balanced fertilizer every 14 days is usually sufficient. As the trees mature, the amount of fertilizer should be increased. When trees reach 7 to 8 months, 1–2 lbs of a complete fertilizer should be provided every 2 months.