If you do fall ill and need advice you can call the Tokyo Metropolitan Health and Medical Information Center on 5285-8181. The centre is open every day from 9am till 8pm and can provide information in English and Spanish. There is also an emergency translation service for foreigners needing medical attention while in Japan: 03-5285-8185 (open daily).
Using the following website you can find hospitals and clinics near your location in Tokyo:
Or use this webpage to locate one near the train or subway station of your choice: