import re
s="C+11.,18.,25.6.,2.,23.7.,27.8.23"
rx = r'\b(\d{1,2}(?:\.,\d+)*)\.(\d{1,2})\b'
results = [(days.split('.,'),month,) for days, month in re.findall(rx, s)]
print(results)
# => [(['11', '18', '25'], '6'), (['2', '23'], '7'), (['27'], '8')]
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