I am a classical homeopath and I have additional information for you.
I agree that typically, we would give carcinosinum once, and watch the response for a period of time. This might be 1 to 2 months.
Secondly, most homeopaths do not repeat nosodes such as carcinosinum if there is a better indicated polycrest, or "constitutional" remedy.
Thirdly, if we were to repeat it, a higher potency might be indicated, such as a 1M rather than a 200C.
Fourth: the fact that your symptoms came back might indicate the need for a much different remedy.
In fact, nosodes such as carcinosinum are often used to simply stimulate the case, so that the next remedy cures the problem once and for all.
At this point there are at least 129 remedies to consider in the differential, and this takes proper interview, exam, and repitorization.
Therefore, you should not take this on your own, you should consult with the previous homeopath, or a new one if you are unable to find the previous doctor.
The goal in homeopathy is to cure the individual long term, not treat a symptom.
These are not drugs, but, there is potential harm to overdosing on a nosode.
A> confuse the case.
B. Suffer un-needed aggravation of existing symptoms.
C. Causing a "proving" in which you develop new symptoms that then have to be removed.
You have good classical homeopaths in the UK Let me know if you need some contacts.