Can you see black specks in their ears. Looks like dirt.
If so, most likely mites.
You need to go to the vet really. I am not a vet so wouldn't want to tell you some home remedies.
Its also really serious if it gets out of control. Obviously you have to really neglect the situation for it to get out of control but when it does its really bad. Can eat their ear drums, even eyes etc. If it damaged their hearing they might be more likely to get hit by a car so its worth going to vets.
I know thats the most serious end scenario but just letting you know so you can go to vets now when its no issue.
Ok thanks I'll take them to the vets .. I was just fed up that last time they didn't check for mites, just said it wouldnt be and gave me very expensive all killing drops that another vet later told me was overkill