The four humours were each assigned to a specific quality :blood-warm,wet; phlegm-cold,wet; yellow bile-warm dry; black bile-cold dry. There were many inspections that the medieval healer did to measure the balance of the humours within the body. Although  these diagnoses were thought to be quite precise during the medieval time, they were usually incomplete. A visit to the physician usually included inspection of blood, feces, and urine, and taking the pulse, but only in rare cases all of the above were included[3]. Blood was checked for viscosity, hotness or coldness, "greasiness", taste, foaminess, and rapidity of coagulation. Medieval healers especially believed in the power of monitoring ones pulse for diagnosis. An anonymous treatise from the thirteenth century describes the varieties of pulses that can be  found and what they describe:

     If an imbalance were found there were many ways that the healers or physicians tried to cure the imbalance. Some of the remedies included: diet alteration, blood letting, "purging" or puking, surgery, and probably the most popular herbal cures. It was believed that the humours were the end product of food consumed, therefore a proper diet was absolutely essential to the maintenance of health[1]. Surgery was usually performed as a last resort if the physicians had already attempted to cure the imbalance using the less invasive cures.
     The most popular Medieval surgery was bloodletting. I believe that this was the most common surgery for patients with very severe symptoms because the physicians were aware that blood could be found in all parts of the body, and if an individual had bad blood this could cause extreme pain and suffering throughout the entire body. The Medieval thought was that letting some of the blood out of the body would restore the balance between the four humours and the patient would eventually be cured. To help ease some of the pain that a patient underwent during the blood letting process hemlock was sometimes ingested. If used in the proper amount hemlock could be a very affective pain reliever. But physicians during the medieval time period were not always  highly educated or experienced with the use of hemlock. This led to some patients being overdosed with hemlock which was a very painful event by itself and could lead to death. I would guess that some patients were given hemlock before the blood letting was to occur but took too much which caused their symptoms to worsen. This probably led the physician to start the blood letting process. The pain that a patient went through during this process is unimaginable. Not only was the patient suffering from the initial ailment that led to the surgery but now they were suffering from an overdose of hemlock and their blood being drained from their body. I imagine that plenty of patients with severe symptoms during the medieval period met their death in a fashion similar to this.
    If the ailments were not severe enough to necessitate surgery the most popular method of treatment was the use of herbal or drug therapy. The ability to identify and prepare drugs, along with knowledge of their therapeutic properties, was therefore an essential part of the repertory of most medieval healers[1]. The drugs used by the healers were usually made of up natural herbs, but animal and mineral substances were also used, depending on the healers' preference. Examples of common treatments for particular ailments included putting hemlock on painful thighs and joints. This practice goes back to the ancient period where hemlock was believed to cure symptoms similar to arthritis. Hemlock wasn't the only cure that sometimes did more damage than it helped. Other drug remedies that more than likely caused the patient more discomfort than he would have felt without any treatment included the use of pig manure to cure nose bleed.