Thank you for reaching out to us.
At any point in the cycle, when a woman has staining that does not make her niddah, she is not niddah. That means that fundamentally she is permitted to have relations.
However, we usually advise that a woman in this situation abstain from relations as a precaution against a flow beginning during relations. Kissing or sharing a bed would be permitted, though it would be advisable to refrain from conduct that may lead to relations.
Additionally, a woman who consistently has non-niddah staining prior to her flow may be considered to have a veset haguf, a veset linked to bodily signs. Based on what you write, it sounds as though you have a veset haguf for premenstrual staining accompanied by cramps. That means that you should observe a veset after your staining begins when you reach the minimum interval between the onset of premenstrual staining with cramps and the onset of your flow. For example, if the flow regularly starts two days or more after premenstrual staining begins, you would observe a veset on day two from the beginning of that staining.
Please be in touch with any further questions.