H2 O2, hydrogen peroxide. Paid 30 Baht for a 250 ml bottle at the pharmacy. Poured some into the affected ear and it's foaming & getting warm. Q-tips reveal yellow puss inside. I keep cleaning that out and rinse and repeat. Applied to teeth with a toothbrush also cleans them. YMMV, but the stuff has helped me in locations where I couldn't get the right antibiotics.