3rd Round of Cisplatin

My husband is being treated for Stage 4a tonsil cancer (HPV - SCC) with 30 rounds of radiation and 3 rounds of Cisplatin (at the beginning, middle and end of the RAD treatments). He finished his last RAD on Wednesday 6/12 and was to have his 3rd round of Cisplatin on Tuesday 6/11 but lab report showed low white cell, red cell and other counts. Tested again yesterday and his counts were even lower. Is there a window of time during which he must receive the 3rd chemo infusion? I am hoping he improves over the weekend, but can't get an answer as to whether or not they will do blood work on Monday to see if is counts are high enough to alloow them to do the 3rd round then. I am being told that alot of patients miss the third round of chemo with little or no impact on the outcome. My husband doesn't want to give up. The third treatment is important to him. Does it make since for me to ask if ther are other chemo drugs that could be given instead of the Cisplatin if his counts aren't high enough? Or other options to relieve my husband's concern about not getting the 3rd infusion?