Calf pain/tightness

I’m training for my third half marathon coming up in four weeks and all a sudden my calves have been flaring up. I took a full week off and felt much better during my long run yesterday but can hardly walk down steps after a 15 minute recovery run today. I know I should scale back and rest a bit now so I’m not feeling terrible next month but struggling to find the balance of rest while still staying in shape. Any advice on how to find that balance or any good recovery techniques?