Greetings, sorry about the pain.
Knee gap that you are talking about is usually called osteoarthritis. Reduced knee gap not a concern, if you could send x ray I will suggest best possible treatment.
Next Steps
without waiting or wasting time see a physiotherapist specialised in trigger point therapy and posture correction your knee pain will be solved. remember it will take 2 weeks to see 20-30% improvement and another 6 months to full recover and the knee gap will increase over this time.
Health Tips
if you have any questions about this still do let me know. never rush to do knee replacement surgery.