Diddy, you have two issues (that may or may not be related):
1) "tailbone pain (primarily when sitting)"
Your spine doctor is dealing with it.
2) "dabs of blood on toilet paper on occasion when wiping"
It's none of your spine doctor business.
You need to see a gastroenterologist (GI specialist) to get colonoscopy done and exclude colon cancer.
Blood in your stool may be caused by hemorrhoids, benign polyps, cancer etc.
Only colonoscopy would help to figure this out.
58 yo male at diagnosis: T1bN0M0, 0/15 nodes, low grade/moderately differentiated adenocarcinoma
03/2016 colonoscopy: 2 small polyps removed in left colon; CEA = 1.3
04/2016 colonoscopy: caecum sessile 3.5 cm polyp piecemeal removed with kind of clear margins
05/2016 "prophylactic" laparoscopic right hemicolectomy - bleeding, leak, infection
06/2017 CT scan, colonoscopy OK; CEA = 1.6
A lot of funny stuff discovered by CT scans in liver, kidney, lungs, arteries, gallbladder, lymph node, pancreas