Is my spironolactone no longer working because of the tretinoin?

No, the cause maybe more complex than that, as levels need to be monitored. Spironolactone can be increased by your physician, dose can range from 50 mg all the way to 200mg or higher. DO NOT increase the dose unless supervised, as potassium levels must be monitored. In most cases, upping the dose by one tab a day sort out your acne. 
Acne can be treated with peels, vitamin A creams- retinol, as well as good skin care including correct use of cleansers, exfoliants and in females make up. The use low level laser emission devices such as blue light- omnilux as well as a variety of peels such as BHA or Lactic Acid peels can address acne. Diet plays an important role in the management of acne, as do supplements such as zinc. Finding the correct combination for your skin type is the key, as everyone has a unique pattern of acne. Some have blackead acne and clogged pores – peels and retinol help in this context. Some have papular pustular acne- phototherapy – LED, and Kleresca is indicated in this subgroup. Do not underestimate the importance of dietary control.

If all else fails, a general dermatologist can prescribe medication to address hormonal issues, or tablets that decrease oil production. All the best.Dr Isobel Walker.  Brisbane. Australia.