I was Poked by a cactus. now finger is swollen and painful?

It sounds like you may have sustained a puncture wound from the cactus spines, which can cause swelling and pain. It's important to clean the area gently with soap and water to prevent infection. If there are any visible spines, try to remove them carefully with tweezers. If the swelling persists, increases, or if you experience severe pain or signs of infection (like redness or pus), consider seeing a healthcare professional for further evaluation and treatment.