Low performance in bed, Vaginal Dryness,

Dear Doctor, I am a working Woman aged 40 Yrs with existing Condition of Rheumatoid Arthitis and under it's medications for almost 10 years and a history of Hypo Thyroid. I have found that my interest in sex is slowly diminishing and after a days work I get tired and go to bed. In weekends also we rarely have sex. Since my Vagina is most of the time dry, I get difficulties while penetration by my hubby and it's always painful. First of all I rarely get aroused and if I get aroused it's always during morning time while we get up and it's not ideal time as our kid gets up and we face privacy concerns. My question is , is there something to help me sustain my energies during late night times so that we can enjoy pleasing sex sessions. I can only cope with missionary position due to my health reasons. Please suggest how I improve my performance and sustainability and address my vaginal Dryness issues. I also get mood fluctuations if I am not satisfied due to to vaginal Dryness.