CRANSTON — When Deb Crabtree contracted COVID-19 in November, she experienced several of the telltale afflictions of coronavirus disease: shortness of breath, nausea, dizziness, headaches and what she describes as “vague confusion” — a feeling of being “foggy.” Crabtree, 60, a registered nurse, did not require hospitalization, but she did miss several weeks of work. She returned at the end of December. Her symptoms had cleared. All but the headaches. She was not prone to them before, but now they are with her daily. And that places her among the so-called long haulers — people w...