I'm coming to that," said Jim. It isn't that I doubt the investment. Don't blame yourself for that; you showed a fine sound business instinct: I always knew it was in you, but then it ripped right out. I guess that little beast of attorney knew what he was doing; and he wanted nothing better than to go beyond. No, there's profit in the deal; it's not that it's these ninety-day bills and the strain I've given the credit - for I've been up and down borrowing, and begging and bribing to borrow.
(From The Wrecker by R. L. Stevenson and L. Osbourne, chapter X, published 1892) https://en.wikisource.org/wiki/The_Wrecker_(Stevenson)/Chapter_10
What does the strain I've given the credit mean in this context? Especially, what does I've given the credit mean there? In particular the word credit troubles me. Thank you very much in advance :)