i had the same thing this year. i shot a buck up hill at 30 yards. the hit was perfect at that angle and should have been a heart shot but it wasnt. when it went in it went straight down. so i caught one lung. i had fat on my arrow with no blood. began tracking and was able to find lung blood after about 20ft. bright red... i am not thinking this is what you have unless you have bright red blood that seemed to be spraying with a great deal of it at times. if you do not have that you skimmed his brisket. but if you have what i described above you hit one lung and he could still live.