All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.
First of all, we ask Allaah to make you steadfast on Islam and to help you to obey Him. You should know – may Allaah enable you to do good – that what would ease the hardship that you are experiencing is to keep yourself attached to Allaah and to know that every harm that befalls a believer in his/her body, self or property, if he/she keeps patient and seeks the reward from Allaah, then he/she would get a great reward from Him.
As regards your question, the maximum period of menses is 15 days. So, if the period of bleeding exceeds 15 days, then it becomes clear that the woman has bleeding outside her menses.
What we understand from your question is that you have discharges outside your monthly period and that the bleeding exceeds the duration of 15 days. In this case, you are obliged to do what a woman who has discharges outside her monthly menses does. So, if you know your monthly periods before you started having discharges outside the time of monthly period, then you should refrain from praying and fasting for the time period of your regular menses and you should consider yourself as being in menses, and any discharges that you might have after this period of time, you should consider it as having discharges outside the time of monthly period.
However, if you do not know your regular monthly period and you cannot distinguish between the menstrual bleeding and the bleeding outside your monthly menses – as it is understood from your question – then you should refrain from praying and fasting for six or seven days each month according to the habit of your close female relatives and you should consider this period as menses and after the expire of the time period that you consider as menses, you should perform Ghusl and put a pad or cloth on your private parts and perform ablution for each prayer after its time has begun and pray with this ablution the obligatory prayer and any supererogatory prayers you may wish to perform until the time of this prayer expires.
After having performed Ghusl during the time period that is considered as having discharges outside your monthly periods, all the rulings of women who are in a state of purity apply to you. So, you are obliged to pray and do what we have mentioned as putting a pad or a cloth on your private parts and then perform ablution for every obligatory prayer and you must fast Ramadan. You may also recite the Quran and touch it and do all the matters that women who are in a state of purity do, until such time that you consider as being in menses comes, then you should refrain from fasting and prayer. You should do this each month until Allaah cures you.
For more benefit on the maximum limit of menses, the minimum limit of purity, and a woman who has regular menses, and the one who can distinguish between her bleedings and the one who cannot do so, please refer to Fataawa 83621, 91444 and 129256 and 152881.
Allaah Knows best.