Thanks for query on hcm.
According to your working pattern pain is usually due to some extra,unequal pressure on the left knee.There might be some internal bleeding called haematoma formation which you feel like lump.
You have to change your working pattern and avoid any weight bearing on knees.Wear knee cap during working hours.
Take nsaid with serretiopepdase to subside pain,inflammation,swelling.
B12,calcium,d3,minerals supplement will be helpful.
If pain is recurrent after routine treatment than go for x-ray of that knee and start treatment under guidance of orthopedician.

hello dear
thanks for your query at HCM
lump on the knee, constantly working on floor could bu due to bursa.
bursa is small pocket of fluid collection in friction area usually knee, medial malleolus, soles etc.
The primary symptom of prepatellar bursitis is the swelling of the area around the kneecap. It generally does not produce a significant amount of pain unless pressure is applied directly to the swelling. The area of swelling may be red (erythema), warm to the touch, prepatellar bursitis generally does not affect the range of motion of the knee, though it may cause some discomfort when the knee is completely flexed. Flexion and extension of the knee may cause crepitus.
Prepatellar bursitis is caused by either a single instance of acute trauma to the knee, or repeated minor trauma to the knee. The trauma can cause extravasation of nearby fluids into the bursa, which stimulates an inflammatory response
Non-septic prepatellar bursitis can be treated with rest, the application of ice to the affected area, and anti-inflammatory drugs, particularly ibuprofen. Elevation of the affected leg during rest may also expedite the recovery process.Severe cases may require fine-needle aspiration of the bursa fluid, sometimes coupled with cortisone injections
hope i answered your query
regards